The recent development on wearable and stretchable electronics calls for skin conformable power sources that are beyond current battery technologies. Among the many novel energy devices being explored, triboelectric nanogenerator (TENG) made from intrinsically stretchable materials has a great potential to meet the above requirement as being both soft and efficient. In this paper, we present a lithography-free and low-cost TENG device comprising a porous-structured PDMS layer and a stretchable PEDOT:PSS electrode. The porous PDMS structure is formed by using self-assembled polystyrene beads as the sacrificial template and it is highly ordered with great uniformity and high structural stability under compression force. Moreover, the porous PDMS TENG exhibits improved output voltage and current of 1.65 V and 0.54 nA compared to its counterpart with non-porous PDMS with 0.66 V and 0.34 nA. The effect of different loading force and frequency on the output response of the TENG device has also been studied. This work could shed light on diverse structural modification methods for improving the performance of PDMS-based TENG and the development of intrinsically stretchable TENG for wearable device applications.